600 ain't much for target shooting, it's only NRA Midrange.
A 175gr .308 match bullet will handle that just fine, as will a 155gr match. Some of the guys used to use 190s and some now use 200+gr for F-TR, but unless you are talking competition, that isn't necessary.
I've never run numbers on the .25s, but assuming you have the twist for it, I'll bet the 115 Berger .25s would do just fine. It's BC is very comparable to the 155.5 Berger Fullbore. It looks like the '06 has 200fps on the 308 to boot.
